基于CMIP6模式模拟的不同排放情景下的2015~2100年北极通航风险评估

Risk Assessment of Arctic Navigability under Different Emission Scenarios Simulated by CMIP6 Models from 2015 to 2100

摘要: 在全球变暖背景下，北极海冰持续消退为北极航道通航提供了有利条件，但近地面风场变化也增加了通航不确定性。本文基于CMIP6中对北极气候模拟性能较优的多模式集合平均结果，构建综合考虑海冰厚度、海冰密集度与近地面10 m风速的海冰–风综合风险指数(CRI)，定量评估了SSP1-2.6、SSP2-4.5、SSP3-7.0和SSP5-8.5等四种情景下2015~2100年普通商船在东北航道、中央航道和西北航道的通航风险。结果表明：(1) 21世纪北极通航风险整体呈下降趋势，但空间差异显著。高风险区主要位于格陵兰岛以北海域和加拿大北极群岛附近，至21世纪末该区域CRI仍普遍高于0.4，表明该区域在评估标准下仍不具备通航条件；低风险区由欧亚边缘海向极区扩展，在SSP5-8.5情景下超过60%海域可满足通航要求(CRI < 0.2)。(2) 未来北极通航条件存在显著季节差异，夏季最优、冬季最差。在中高排放情景下，夏季东北和西北航道普遍具备通航条件(CRI < 0.2)，而冬季大部分区域CRI仍高于0.4，无法通航，表明季节性海冰覆盖仍是限制冬春季通航的主导因素。(3) 在SSP2-4.5情景下，西北航道夏季CRI下降40%~50%，中央航道全年CRI下降25%~30%；但在SSP5-8.5情景下，夏季东北航道CRI后期出现小幅回升，表明在海冰持续减少的背景下，近地面10 m风速增强可能反而会增加通航风险。

Abstract: Under the background of global warming, the continued retreat of Arctic sea ice provides favorable conditions for the navigability of Arctic shipping routes; however, changes in the near-surface wind field also introduce uncertainties to navigation. This study employs the multi-model ensemble mean of the Coupled Model Intercomparison Project Phase 6 (CMIP6) models that demonstrate superior performance in simulating Arctic climate conditions. A comprehensive Sea Ice-Wind Composite Risk Index (CRI) is developed, integrating sea ice thickness, sea ice concentration, and near-surface (10 m) wind speed, to quantitatively assess the navigational risks for ordinary merchant vessels along the Northeast Passage, the Central Arctic Passage, and the Northwest Passage from 2015 to 2100 under four scenarios: SSP1-2.6, SSP2-4.5, SSP3-7.0, and SSP5-8.5. The results indicate: (1) In the 21st century, the overall navigational risk in the Arctic exhibits a declining trend, but with significant spatial heterogeneity. High-risk areas are primarily located in the seas north of Greenland and near the Canadian Arctic Archipelago, where the CRI remains generally above 0.4 by the end of the century, suggesting that these regions are still not navigable under the evaluation criteria. In contrast, low-risk areas expand from the Eurasian marginal seas toward the polar region, and under the SSP5-8.5 scenario, more than 60% of the Arctic waters meet the navigability requirement (CRI < 0.2). (2) Future Arctic navigability shows pronounced seasonal differences, being most favorable in summer and least in winter. Under medium-to-high emission scenarios, the Northeast and Northwest Passages are generally navigable in summer (CRI < 0.2), while in winter, most areas exhibit a CRI exceeding 0.4, rendering navigation infeasible. This indicates that seasonal sea ice cover remains the dominant factor restricting navigation in winter and spring. (3) Under the SSP2-4.5 scenario, summer CRI in the Northwest Passage decreases by 40%~50%, while the annual CRI along the Central Arctic Passage declines by 25%~30%. However, under the SSP5-8.5 scenario, a slight increase in summer CRI is observed in the later period along the Northeast Passage, suggesting that intensified near-surface (10 m) wind speeds may increase navigational risk despite ongoing sea ice reduction.